This invention relates to food and more particularly to an expanded, sugarless, semi-moist pet food.
Within the class of foods known as pet foods, there are three basic subdivisions--dry pet food, semi-moist pet food, and moist pet food. The moisture is determined by considering both the water present in the final product and the water combined with the various components that make up the final product. In general, the dry pet food -- due to its low moisture content which is usually less than about 15 percent -- tends to exhibit the greatest microbiological stability and requires no special handling or packaging upon distribution.
At the opposite end of the spectrum is the moist pet food having a moisture content in excess of about 50 percent. Due to the high moisture content of the moist pet food, microbiological stability is a major problem. This problem in a moist pet food is overcome only by heat sterilizing the moist pet food and packaging the moist pet food in a hermetically sealed container. Even with the heat sterilization and hermetically sealed package, refrigeration is required after the package of moist pet food is opened to preserve the leftover pet food for even a short time.
Semi-moist pet food has a moisture content generally ranging from about 15 to about 50 percent. Since semi-moist pet foods are higher in moisture content than dry and lower in moisture than canned, special techniques are required to render it microbiologically stable. This moisture content in combination with special techniques may produce a microbiologically stable food which does not require refrigeration. At the same time, the higher moisture content of the semi-moist pet food provides an increased palatability when compared to the dry pet food. The semi-moist pet food is generally rendered microbiologically stable by using high levels of sugar and solutes. In this fashion, shelf stability without refrigeration is achieved while providing a food having increased palatability relative to dry pet food.
When considering palatability the moist pet foods are the most palatable and the dry pet foods are least palatable. The semi-moist pet foods fall somewhere in between the moist and dry pet foods as to palatability. It follows, therefore, that the semi-moist products provide a higher palatability than dry and provide the convenience of being shelf stable over the canned.
To increase acceptability of a semi-moist pet food for both the pet owner, and the pet, it is desirable to have an expanded pet food for appearance sake and an adequately high moisture content for palatability purposes. However a maintained, relatively high, moisture content and expansion are not customarily compatible. In fact, it is usually required to sacrifice high moisture content for expansion or vice versa.
The expansion of a semi-moist pet food is difficult due to the high moisture content and prevalence of nonexpandable materials such as high levels of meat, sugar, and polyhydric alcohols. The high sugar content in conjunction with the higher moisture content of semi-moist pet food results in reduced expansion, clumping and piece distortion. On the other hand, the presence of sugar provides a great deal of the stability of a semi-moist pet food. The problem thus becomes one of achieving the expansion of the semi-moist pet food and stability of the semi-moist pet food while eliminating the heretofore necessary sugar used to provide stability under semi-moist conditions. In other words, the sugar necessary for stability has an adverse effect on the desired property of expansion. Thus, it has proven difficult to obtain the desired expansion while achieving the desired semi-moist stability.
It is known to achieve microbiological stability in a semi-moist pet food by using high levels of sugar and solutes above about 25 percent by weight of the semi-moist food, and antimycotic, and pH of around 6 to 8. It is also known to use low pH levels of a range of two to five in combination with the thermal pasteurization and hermetically sealed container to achieve a stable packaged product. However, rupture of the hermetically sealed container for a low pH pet food leads to mold and other microbiological defects, which factors indicate this food is not a true shelf stable semi-moist food. Accordingly, it has proven difficult to achieve the desired semi-moist stability and avoid microbiological degradation without the use of the above-referenced stability systems.
A further problem with the use of acid, as a stabilizing ingredient is a resulting sour or acid taste. Such a sour or acid taste renders a pet food less palatable to the pet consuming it. The use of high levels polyhydric alcohols or other solutes in combination with a higher pH also can interfere with a pet's enjoyment of the food. There is a problem in adjusting the balance between the acid content and the polyhydric content and the other stabilizing components to achieve the suitable palatability and stability for the semi-moist pet food.
Thus for both dogs, cats, and other pets it is difficult to reduce solute levels below 20 percent (sugar and polyhydric alcohols for example) without sacrificing both palatability and stability. It is also difficult to provide both palatability and good appearance without sacrificing one for the other.